The following discussion of the background of the invention is merely provided to aid the reader in understanding the invention and is not admitted to describe or constitute prior art to the present invention. This application claims priority to U.S. application Ser. No. 60/529,016, filed Dec. 11, 2003, which is incorporated herein in its entirety including the drawings. Applications related to this application are PCT/US03/36237 filed Nov. 12, 2003 entitled “adenoviral vector vaccine” and U.S. provisional patent applications 60/524,925 (filed Nov. 24, 2003), 60/525,552 (filed Nov. 25, 2003), and 60/529,015 (filed Dec. 11, 2003), all of which are incorporated herein in their entirety including the drawings.
The activation of antigen presenting cells (APCs) which includes the dendritic cells (DCs), followed by loading of the antigen presenting cell with relevant antigens, is a requisite step in the generation of a T cell dependent immune response against cancer cells. Once activated and loaded with tumor antigens, DCs migrate to regional lymph nodes (LNs) to present antigens to T cells. Very commonly, these APCs express insufficient amounts of surface activation molecules which are required for optimal activation and expansion of T cell clones competent to recognize tumor antigens. See Shortman, et al., Stem Cells 15:409-419, 1997.
Antigen presentation to naive T cells, in the absence of costimulatory molecule expression on the surface of the APC, leads to anergy of the T cells. See Steinbrink, et al. Blood 99: 2468-2476, 2002. Moreover, cross-presentation by DCs without CD4+ T cell help also results in peripheral deletion of Ag-specific T cells in regional LNs. See Kusuhara, et al., Eur J Immunol 32:1035-1043, 2002. In contrast, in the presence of CD4+ T cell help, DCs acquire functional ability to cross-prime T cells, resulting in clonal expansion of effector T cells. See Gunzer, et al., Semin Immunol 13:291-302, 2001. This CD4+ T cell help can be replaced with CD40-CD40 ligand (CD40L) interactions. See Luft, et al. Int Immunol 14:367-380, 2002. CD40L is a 33-kDa type II membrane protein and a member of the TNF gene family and is transiently expressed on CD4+ T cells after TCR engagement. See Skov, et al. J Immunol. 164: 3500-3505, 2000.
The ability of DCs to generate anti-tumor immune responses in vivo has been documented in a number of animal tumor models. See Paglia, et al. J Exp Med 183: 317-322, 1996; Zitvogel, et al., J Exp Med. 183: 87-97, 1996. However, DC-mediated induction of immunity represents a major therapeutic challenge. It is considered difficult to ensure that the antigen presenting cells express appropriate adhesion molecules and chemokine receptors to attract DCs to secondary lymphoid organs for priming T cells. See Fong, et al. J Immunol. 166: 4254-4259, 2001; Markowicz, et al. J Clin Invest. 85: 955-961, 1990; Hsu, et al. Nat Med. 2: 52-58, 1996; Nestle, et al. Nat Med. 4: 328-332, 1998; Murphy, et al., Prostate 38: 73-78, 1999; Dhodapkar, et al. J Clin Invest. 104: 173-180, 1999.